Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque

H, W = map(int, input().split())

maze = "#" * (W+2)
for _ in range(H):
  maze += "#" + input() + "#"
maze += "#" * (W+2)

dist = [-1] * (W+2) * (H+2)
q = deque()

dist[(W+2) * 1 + 1] = 0
q.append((W+2) * 1 + 1)

while len(q) != 0:
  v = q.popleft()
  
  udlr = (-W-2, W+2, -1, 1)
  for move in udlr:
    nv = v + move
    if maze[nv] == "#":
      continue
    if dist[nv] != -1:
      continue
    dist[nv] = dist[v] + 1
    q.append(nv)
if dist[(W+2) * H + W] == -1:
  print(-1)
else:
  print(W * H - maze.count("#") + 2 * (W + H + 2) - dist[(W+2) * H + W] -1)